LTP-001

Plasma, which was coined by Irving Langmuir in 1928, is the fourth physical state after the solid/liquid/gas phases. Low-temperature plasma (LTP) is a contradictory condition that involves high energy with free radicals at near-body temperatures and was developed through engineering in the 1990's. Research on LTP in engineering and medical fields has rapidly developed since the 2000's. LTP can be applied through direct or indirect exposure, and there are advantages to both methods. In the medical field, LTP has been found to exert several effects, such as wound healing, hemostasis and anticancer effects, mainly based on different levels of oxidative stress. In the dental field, studies have been performed on LTP applications for general dental procedures, such as restorative, periodontal and prosthodontic procedures, and for oral cancer treatment. Many studies have demonstrated the effectiveness of LTP. Compared with other organs, the anatomical characteristic of the oral cavity is easy direct observation, which is highly advantageous for clinical applications. Due to its good accessibility and efficiency, plasma dentistry is expected to be applied to various dental applications in clinics in the near future.

Lapatinib (LTP) commercially available as lapatinib ditosylate (LTP-DTS) salt is the only drug approved for the treatment of HER-positive metastatic breast cancer. A low and pH-dependent solubility results in poor and variable oral bioavailability, thus driving significant interest in molecular modification and formulation strategies of the drug. Furthermore, due to very high crystallinity, LTP and LTP-DTS have low solubility in lipid excipients, making it difficult to be delivered by lipid-based carrier systems. Thus, the present work reports a new salt form of LTP with a docusate counterion to enhance the pharmaceutical properties of the drug (LTP-DOC). NMR spectra showed a downfield shift of the methylene singlet proton from 3.83 and 4.41 ppm, indicating a lowering of electron density on the adjacent nitrogen atom and confirming the formation of amine-sulfonyl salt through the specified basic nitrogen center located adjacent to the furan ring. PXRD diffractograms of LTP-DOC indicated a reduced crystallinity of the prepared salt. The dissolution, equilibrium solubility, lipid excipient solubility, partitioning coefficient, distribution coefficient, tabletability, and in vitro cytotoxicity of the lipophilic salt of LTP were investigated. The equilibrium solubility data showed that LTP-DOC possesses a pH-independent solubility profile in the pH range of 3.5 to 7.4 with a 3.14 times higher permeability coefficient than commercial ditosylate salt. Furthermore, the prepared LTP-DOC salts showed twice higher log P than the free base and 8 times higher than LTP-DTS. The prepared LTP-DOC was found to have 4- to 9-fold higher solubility in lipid excipients like Capmul MCM C8 and Maisine CC compared to the ditosylate salt. The LTP-DOC salt was tabletable and showed approximately 1.2 times lower dissolution than commercial ditosylate salt, indicating extended-release behavior. A cytotoxicity study of LTP-DOC salt showed an approximately 2.5 times lower IC₅₀ value than the LTP-free base and 1.7 times lower than commercial ditosylate salt with an approximately 3 times higher selectivity index. The investigations strongly indicate a high translational potential of the prepared salt form in maintaining solubility-lipophilicity interplay, enhancing the drug's bioavailability, and developing lipidic formulations.